Why are you so sure that the quota usage is incorrect? The Quota for a FTP User is the quota of the web[ID] linux user, if the quota is not set separately for this FTP user in the ftp user settings. So if you want to check if the quota is correct, run the command:

repquota -avu | grep web1

And you should update your ispconfig version, 3.0.3 is quite old, the current version is 3.0.3.3

Indeed, this morning, the quota was 500MB, I passed it to 1GB when I noticed it was "full". I ran several time :

Code:

quotaoff -avug
quotacheck -avugm
quotaon -avug

But this make no difference... Here are my questions :

1- Is it normal that quota here is 500MB while PureFtp shows 1GB ?
2- Is it normal that usage here is 0 while PureFtp shows 512MB ?
3- If usage really is 512MB, where could I find (and destroy) the (useless) files ? Because my website is only 63MB... I mean the user home dir is 63MB, how could it have written so much files outside of his home ? (this is a tiny website, not very popular...)

Thank you for your precious time Till, you do a really great job !

PS : I'll upgrade ASAP, unfortunately this is not so easy because I had to make some hacks... I don't think this problem is really related with ISP Config anyway, or is it ?

ISPConfig uses Linux system quotas for websites and not pure-ftpd quotas. Linux system quotas are handled by the filesystem automatically and are configured in /etc/fstab. They are used for ftp and ssh users, linux system quotas dont have to be updated manually with pure-quotacheck.

ISPConfig does not use a file called .ftpquota in its default install, so there is no need to update that from ispconfig side. If you use a different setup though, then you might have to use your own scripts.